The goal of this research is to understand the neural mechanisms that underlie object perception in the primate cerebral cortex. The proposed experiments focus on areas V1, V2, and V4, which form the basis of low level and intermediate levels of object processing in the primate visual cortex. The first series of experiments will examine new aspects of the modular and submodular organizations of area V2 and their inputs from V1 and outputs to V4. Optical recording of intrinsic cortical signals will be used to characterize the functional architecture of V2 and to guide injections of neuroanatomical tracers into specific V2 modules or submodules. These studies will determine (1) the pattern of projections of 2-3 adjacent V2 thin stripes to V4, (2) whether V2 thin stripe submodules receive inputs from different populations of V1 blob and interblob cells and project to different portions of V4, and (4) whether V2 contains clusters of neurons that differ in their sensitivity to chromatic of orientation-specific surround antagonism. The second series of experiments will use optical recording of intrinsic cortical signals and conventional microelectrode recording to examine the functional architecture of area V4. These experiments will determine (1) the degree to which chromatic and orientation processing are segregated in V4, and (4) the functional architecture of chromatic and orientation-specific surround antagonism in V4. Overall, these experiments will provide new insight into the modular and submodular organizations of areas V1 and V2 and will lead to better understanding of the functional architecture of V4. The long-term goal of this research is to link the functional properties of specific V4 modules to their connections with V1, V2 and other cortical areas. These experiments lay the groundwork for future investigations of specific V4 modules and their relationship with individual cortical areas of inferotemporal cortex.